Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
va cau » va cac, va dau, va cao
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) or (cac ky)) nang xa hoi. hieu ((va cau) OR (van cau)) thuc vat hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (cac ky)) nang xa hoi. hieu ((va cau) OR (van cau)) thuc vat hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (cac ky)) nang xa hoi. hieu ((va cau) OR (van cau)) thuc vat hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (cac ky)) nang xa hoi. hieu ((va cau) OR (van cau)) thuc vat hanh vi cua tre*.